1. Field of the Invention
The present invention relates to a light-emitting element and a lighting device using the light-emitting element as a light source.
2. Description of the Related Art
There has been a light-emitting diode element (hereinafter, referred to as an LED element) as a light-emitting element, which includes a body including a PN junction structure with a pair of element electrodes in which part of a P layer and an N layer are exposed on a surface of the body. The LED element with such a structure, which is mounted on a circuit substrate and electrically connected to the circuit substrate, for example, through a bump (s), a wire (s), and so on, has been known as an LED package. Such an LED package may include a pair of electrodes disposed on the circuit substrate, a reflecting member, and other components disposed on the circuit substrate. The circuit substrate of the LED package is mounted on a board as a mother board of a lighting device and/or a system with light-emitting properties.
When the LED element is mounted on the surface of the circuit substrate, a PN junction surface has been disposed at a central portion of a LED element body and the pair of element electrodes are positioned to be exposed from the LED element on both sides of the LED element body. The pair of element electrodes are electrically connected to the pair of electrodes disposed on the circuit substrate through indium (see Japanese Utility Model Application Laid-Open No. Sho. 52-157769).
Further, a circuit substrate on which the LED element is mounted is disposed with a predetermined angle inclined to a specific direction (see Japanese Utility Model Application Laid-Open No. Sho. 63-022759).
FIG. 12 is an explanation drawing showing a light-emitting element 1 including a pair of element electrodes as a first element electrode 3a and a second element electrode 3b, in a state that the light-emitting element 1 is unfavorably inclined backward on a surface of a board 5, because of a hardening effect of a first solder 9a and a second solder 9b through a reflow process. A lower surface of a first element electrode 3a should be in contact with a first electrode 7a of the board 5 and a lower surface of a second element electrode 3b should be in contact with a second electrode 7b of the board 5, however, the first element electrode 3a tends to be pulled backward at a first connecting portion P1 that is a rear edge of the lower surface of the first element electrode 3a and the second element electrode 3b tends to be pulled backward at a second connecting portion P2 that is a rear edge of the lower surface of the second element electrode 3b through a reflow process. In other words, the light-emitting element 1 is pulled backward at the first connecting portion P1 and the second connecting portion P1 that are in alignment with each other as an axis of unfavorable inclination caused by a hardening effect of solder through a reflow process.